Back brush



FIG. 1 is a front perspective view of a back brush showing my new design;

FIG. 2 is a top plan view thereof, the bottom plan view being a mirror image;

FIG. 3 is a front elevational view thereof; and,

FIG. 4 is a side elevational view taken from the right side of FIG. 3, the opposite side being a mirror image.

A view of the rear is omitted because the rear is flat and devoid of surface ornamentation. 

CLAIM The ornamental design for a back brush, as shown and described. 